#!/bin/sh sudo
/System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart
-configure -clientopts -setmenuextra -menuextra yes Seanhansell - this
is the command I have been using via Jamf to show the ARD Menu Extra on
High...
You could use an app called Platypus - this allows you to wrap shell
scripts into an app that can then be run at login via MCX, Profile etc.
I've used it in the past for this exact reason and it's never failed me.